Fe XXV Kα Fe I Kα

S XV Kα

•Strong Fe XXV Kα, S XV Kα, and Fe I Kα the GCXE consists of

High Temperature Plasma (HP), Low Temperature Plasma (LP), and

Cold Gas .

•The GCXE is not integral emission of unresolved X-ray stars.

X-ray surface brightness of Fe XXV Kα

factor 3-4 of discrepancy

Average spectrum of the GCXE 　(Uchiyama+13)

Spatial distribution of the GCXE and stars (Uchiyama+11)

The Suzaku Images of the Galactic Center X-ray Emission (GCXE)

Suzaku and other satellites found time variability

of Fe I Kα and hard X-ray from molecular clouds

(MCs, e.g. Muno+07, Inui+09, Ponti+10).

X-ray light echoes of past flares of super massive black hole Sgr A* at the center of our Galaxy.

Key information for activity history of Sgr A*. Accurate past light curve of Sgr A* (in time and fluxes) depends on 3-d distribution of the MCs (e.g. Ryu+13).

1 X-ray Reflection Nebula (XRN): Echo of Past Sgr A* Flares

Line of sight Positions of XRNe (Ryu+13)

Variable XRN Sgr B2 (Nobukawa+11)

700 yr activity history of Sgr A* (Ryu+13)

2-2 Hint of a RP from a Close Vicinity of Sgr A*

If Sgr A* was very active about a few 105 years ago as is suggested by the GC south plasma, it might also leave a RP at a close vicinity of Sgr A*.

Suzaku found a hint of RP near Sgr A* (l = 0°.1, b = -0°.1 ). The plasma also shows a hint of Compton shoulder of the 6.4 keV line.

•The fitting of a CIE plasma model leaves residuals at ~ 6.7 keV and ~ 6.3 keV.

•RP model and Compton shoulder of the 6.4 keV line significantly improve the fitting.

Suzaku spectrum near Sgr A* (l = 0°.1, b = -0°.1)

New Sciences of the GCXE to be unveiled by ASTRO-H

We propose three pointing observations, which play complementary roles.

(1) The Sgr A* region is for the study of Sgr A* and its vicinity.

(2) The GC East region is the strongest in Fe I Kα (XRN) (“MC1” in Ponti+10).

(3) The GC West is the region of pure HP and LP components with no bright XRN.

Galactic longitude

Fe XXV Kα line image Fe I Kα line image

(2) GC East

(3) GC West

SXS FOVHXI FOV 10 pc

(1) Sgr A* (2) GC East

(3) GC West

(1) Sgr A*

Proposed 3 positions overlaid on Suzaku XIS images

o.2 　　　 0.1 　　　　 0.0 　　　　 -0.1 　　　 -0.2 (deg) 　

o.2 　　　 0.1 　　　　 0.0 　　　　 -0.1 　　　 -0.2 (deg) 　Galactic longitude

1. Accurate History of Past Sgr A* FlaresSXS simulation spectrum of (2) – (3)

Compton shoulder of Fe I Kα

Fe I KαFe I Kβ

SXS simulation spectrum of (1) vs.(3)

Fe XXV Kαcomplex

Fe XXVI Lyα

　　　　　　 Suzaku spectrum shows a hint of the

　　　　　　　 Compton shoulder of Fe I Kα.

We can obtain pure Fe I Kα spectrum by subtracting (3)

GC 　 West data from (2) GC East data.

The shape of the Compton shoulder gives 3-D position

of the MC. 　　 Then we can obtain more accurate light

curve of Sgr A*.

In a photo-ionized plasma formed by a past Sgr A* flare, the temperature ratio of ionization (kTz) to electron (kTe) should be higher near Sgr A*. We can see the difference of kTz/kTe between (1) Sgr A* and (3) GC West regions.

2. Plasma Diagnostic for Sgr A* Activities

Sgr A* region (kTz/kTe = 3.0) GC West (kTz/kTe = 1.5)

CIE RP

kTz/KTe=1.0 1.5 3.0

G ratio

(x+y+z)/w0.70±0.04 0.88±0.0

41.84±0.0

7

3. Non Thermal Emission and a Coming Sgr A* Flare

Fe XXVI Lyα1 & Lyα2

100 km/s red shift

50 km/s blue shift

200 km/s broadening

SXS simulation spectrum of (1), (2), and (3)

SXS & HXI wide-band simulation spectrum from (1)

(1)

(3) (2)

High-quality spectra of the GCXE with SXS/SXI/HXI give us the first opportunity to investigate• exact nature of hard X-ray (possibly

non-thermal) emission with no energy gap between 0.5 and 50 keV.

• coming flare of the nearest massive black hole Sgr A* (Gillesen et al. 2012).

Doppler shift of the GCXE lines tell the dynamics of the GC plasma and XRNe. Do they show the same Galactic rotation curves as stars ?

4. Dynamics of the GCXE Plasma and XRNe

5. The GC: a Treasure Box in Astrophysics

We have made many “unexpected” discoveries from the GC with Ginga, ASCA, and Suzaku, such as the GCXE, XRNe, RP and etc. The high-quality spectra of ASTRO-H will surely provide new “unexpected” discoveries, because the GC is full of mystery and a treasure box in astrophysics.